I have trouble connecting my adabox010 trellis M4 to connect to my ubuntu linux computer. The demo code is running on the trellis but my computer is simply not recognizing anything. dmesg shows nothing at all after clearing and reconnecting the trellis.

As a sanity check, verify your USB cable by using it to connect some other, known-working device to the computer.

There's a plague of charge-only cables out there with USB connectors at both ends but no wires for the data. We see people get caught by them every day, and it's become normal for people to say they had to try three or four cables before finding an actual USB cable.

Just swapping cables has no diagnostic value. We need to see the positive response of a known-working device making a USB connection to rule out the false negatives of charge-only cables.

There's a known issue with USB-3 ports causing trouble for microcontrollers.

High-speed USB operates at 480MHz, and the device recognition process starts with a burst of data at that frequency. The theory is that any device that can handle high-speed data will respond, and slower devices won't notice the blip. Microcontrollers whose CPU clocks run in the tens of megahertz can't read the high-speed data, but the high and low voltages can mess with the input circuits connected to the pins. For boards that handle USB internally, the high-speed data can crash the bootloader, or at least the parts that handle USB communication.